Hinges are provided to have little resistance to rotation with a mechanism to transmit safely the trust and shear forces that comes from the member to be supported. In the analysis of hinged structures it is assumed that the bending moment at the hinge is zero.

This can be achieved only by providing entirely free to rotate condition. Such ideal hinges can not be constructed, since friction and other inevitable restraining factors can not be avoided.

Practically, it is aimed to ensure that the flexibility of the hinge
be considerably greater than that of any other portion of the structure of
which it is a part. This is done to have negligible errors as a very small
moments in the hinge is occurred as compared to the moments in the in the
structure proper. The use of hinges is not restricted to arches and equally
useful in rigid frames, bridges as well as in buildings preferably for
long-span single-story frames.